thales how do you set up "needing a password to switch to the main profile"
I just set a long password as the unlock method of the owner profile. Just the thought of typing it in discourages me.
thales also isn't it the case that everytime you restart the phone you need to log in to the main profile and then switch to the dumbphone profile?
Yes, that is correct. You could try to limit distractions by keeping the owner profile empty.
thales if I have the password of the owner profile all I need to get around these restrictions is to restart the phone and log in to the main profile
You don't even need to restart, you can just switch users. The idea is that you set it up in a way where even if you want to get around limits, it'll be too much of a hassle and you'll give up on the idea. It depends on how determined you are. Also it's good to know that in case of an emergency you can bypass the limits.
thales is your setup just solely for a limited time as apposed to long term use?
Nope, I use it long term.
If you are really worried about using the owner profile to get around limits you could also install Timelimit.io in there and keep the password somewhere else or have a trusted friend set it.